We spend most of the summer in our 24' 5th wheel. It is not large, but it surprises me (and my husband!) how much stuff I can get in it. My husband usually fishes and I quilt, quilt, quilt. I always take both my sewing machine and my serger, cause I love to make baby clothes, too. Then I have my cutting mat and my iron and my small ironing board, my GO cutter + dies, fabrics, batting, notions, etc.
I have found that there is really a lot of storage in these things. I don't leave everything out when I am not sewing cause there are plenty of places to put everything.
My husband always says he wonders if there is going to be enough room left for all the things we need, like food, clothes, towels, etc. He hasn't been disappointed yet, though.
I love sewing in our little 5th wheel!